Best practice for working with old drawings as sketch pictures?

[KirbyWan]

Howdy all,

I regularly work with old drawings of parts and need to remodel them in SolidWorks. I was wondering what people felt were some best practices to use when working with drawings as sketch pictures in SolidWorks. Here are my issues and how I handle them.

1. If I only have one drawing or a small drawing to deal with I crop it so I have nothing but that part in a picture and then bring it into SolidWorks. Drop a horizontal or vertical line over one in the drawing then measure the angle with the horizontal and adjust the angle of the drawing so we're plumb. drop a line along the largest measurement I can find on the drawing then measure it to adjust the scaling to match. If I am working with a drawing that has station lines, butt lines and/or water lines, and it make sence to me I will drop a line along a reference line on the drawing and translate the sketch so the drawing is now in the same coordinate space as Solidworks. Woo Hoo success. But I usually have another issue to deal with.

2. If the drawing extends across what would normally fit in a 3:4 ratio box such as J size drawings it is usually broken up on the microfilm which I usually get as a TIF or PDF file. I could

a) bring each portion of a picture in to SolidWorks on its own sketch and do the rotation - scale - translate steps, but SolidWorks gives me a bunch of errors about not having enough memory to complete this task.
b) Use an image matching program to join each image together first then bring one large image in, but with each drawing being a bit off in angle and scale I'm worried that an image joining program might distort the image.
c) Use a vectorizor like WinTOPO and vectorize first then bring in the vector file into SolidWorks (I just started messing with this and am not sure of how well these work.)

Or I could do some combination of the above. I could join pictures then vectorize or something else. After messing with vectorization for a few minutes I'm a bit averse because I don't know the tools that well.

How have other people faced dealing with one drawing sheet broken over several pages?

Thanks for your help!

-Kirby

Kirby Wilkerson

Remember, first define the problem, then solve it.

 

[CorBlimeyLimey]

I wouldn't bother with the sketch picture routine. I'd simply create the model from the 'paper' copy dimensions ... unless the paper copy had no dimensions.

 

[KirbyWan]

The drawings I am working with are not the discrete part drawings, but the assembly drawings. They will have some critical dimensions and station lines, but they are not fully dimensioned. Usually I'm missing the definition of the edge shape of a panel while all the dimensions from the panel edge to details are given. If I'm lucky I can get loft line data and work from that, but as a general rule I'm creating my model from drawings some of which were done in the 60's.

-Kirby

Kirby Wilkerson

Remember, first define the problem, then solve it.

 

[DesignerGuy16]

Have you tried using photoshop, or a similar program to splice the pictures together?

Solidworks handling sketch pictures isn't the most accurate way to go anyways. Since scaling and location can be very easily distorted.

James Spisich
Design Engineer, CSWP

 

[MikeHalloran]

Last year at this time I had mostly finished a model of a natural gas engine, working from AutoCAD drawings of two views of the outline, a dozen partial drawings of the various options installed, some photographs, and as the deadline approached, the actual engines. Luckily, the drawings were in dwg format, included some waterlines and butt lines, and were mostly to scale, except where somebody had fudged a few casting fillet radii.

I found it was most effective to remove the chaff in AutoCAD, then use SW's 2D to 3D tools to place and extrude the partial images.





Mike Halloran
Pembroke Pines, FL, USA

 

[KirbyWan]

Thanks to all who responded.

Jspisich:

Where you suggest using photoshop, this is where I was suggesting in b) above to use an image matching program. Some of these programs can be very sophisticated and inteded to use multiple shots of a building from one location to stitch an image together. You can usually pick out parts of the image and say this is supposed to be vertical and that should be horizontal and such and such are evenly spaced and it will stretch you image to fit. But I'm not sure if this level of detail is acceptable. I need something a bit more advanced then just a crop tool because each image could be canted or scaled differently.

Generally I think of the SolidWorks tools to deal with pictures to be very strong. The only weakness is that while it can scale the X and Y axes independently, It can't correct for skew, that is horizontal and vertical not being orthagonal and trapazoid errors. But this has never been a problem for me so far since most scans of drawings are pretty square. It could come in handy for tweeking pictures though at that point it might make more sence to go for the image editing tools.

Mike,

I wish I had .DXF/.DWG files. What I do have for my current project are fairly good .TIFF files. I often have crappy, blotchy PDF files. Note the wise. if you scan a D or J size drawing and save it as an 8.5" X 11" PDF there is not enough resolution to read the title block or any dimensions. Very frustrating.

Once again thanks to everyone for their suggestions.

-Kirby

Kirby Wilkerson

Remember, first define the problem, then solve it.

 

[KevinDeSmet]

Kirby,

You make a great point. Even in Photoshop it can be difficult to accurately de-skew photographs. Is it even possible to any reasonable accurate extent?

Certified SolidWorks Professional